Adsorption and electrokinetic studies in kaolinite/anionic polyacrylamide/chromate ions system

The use of clay minerals as adsorbents in the removal of heavy metal ions is of great interest for many researchers. Most of the studies concern the impact of various factors, such as pH value, temperature, adsorption efficiency and surface modification of individual minerals, on the heavy metal accumulation. Various heavy metals can be captured from the solution by clay minerals or their composites. The latest one can be obtained by mineral modification by organic compounds or polyelectrolytes such as anionic polyacrylamide. The polymer presence on the solid surface may contribute to stronger accumulation of heavy metal ions and as a consequence to clear reduction of their availability for organisms. Moreover, it may stimulate the particle aggregation and increase the soil resistance for erosion significantly. For this purpose, the anionic polyacrylamide impact on the chromate ions adsorption on the kaolinite surface was studied. The effects of pH value, type of anionic polyacrylamide, heavy metal ion concentration and order of adsorbates addition to the clay mineral system were determined. Spectrophotometry, potentiometric titration and microelectrophoresis methods allowed to describe the adsorption, stability and electrokinetic properties of the examined systems. In such a way the immobilization possibilities of heavy metal ions in the polymeric surface layer were investigated.